As is well known, high grade metal materials are used in a hull in large quantities, and when it becomes a scrapped vessel, it is broken up into pieces of metal materials (bar materials, plate materials and shape steels) to make articles of commerce or scrapped materials for sale.
As a prior method of breaking up a hull, the portion of a hull floating on the sea which is above the water surface is cut into large masses (generally called as large separation), these masses are lifted by means of a marine crane or a land overhang crane and disposed on the land and then cut into small masses (generally call as small separation). After the end of the breaking-up of the portion appearing above the water surface, the portion below the water surface is towed onto shallows, and waiting the ebb-tide the hull appearing above the water surface is subjected to said large separation in the same manner as described above and then to said small separation.
In the case of said prior art breaking-up method, it is required to have a position to moor the hull, shallows, a quay to land the broken-up bodies and a wide place where the small separation is carried out, and it is impossible to perform the breaking-up operation everywhere. As another problem, the large separation and the small separation are carried out at different positions separated from each other, so that the transportation by a crane is required, and thereby the working number required for said transportation amounts to as large as 30% of the whole working number of the breaking-up. In addition, there is a further problem in which many workmen are required because the breaking-up working places are separated into a plurality of positions.
Under such circumstances, in the prior art working method, there are a severe restriction in the breaking-up place as well as a requirement of many workmen, so that scraps and metal materials which can be used immediately become inevitably expensive.